After installing java3d 1.1.2 OpenGL on WINNT, I'm still getting the
non-congruent transform error. However, it seems to occur much less often
now (in fact, I have only gotten it once since the new install). I cannot
say 1.1.2 fixed the problem because I might be just getting "lucky", since
I'm still not sure about the source of the problem. I'm not using
Matrix4d.
-Tachio
On Thu, 10 Jun 1999, Ellery Chan wrote:
> It may be "just a bug", as you say. I was getting that exception. In
> my case it was due to a Transform3D bug which they say won't be fixed
> until the next release after 1.1.2. The source of the problem is that
> when a Transform3D is set from a Matrix4d the Transform3D does not
> always correctly determine the type of matrix. See my included test
> code.
>
> -ellery-
>
> Tony Burrows wrote:
> >
> > At 10:33 09/06/99 -0400, you wrote:
> > >On Tue, 8 Jun 1999, Tony Burrows wrote:
> > >
> > >> At 13:07 08/06/99 -0400, you wrote:
> > >> >Hi,
> > >> >
> > >> >I have a behavior that changes rotation (in x, y and z) and translation
> > >> >(in x and z) above ViewPlatform. Basically, it acts like a camera
> > >> >orientation/position controller. It works most of the time but sometimes,
> > >> >I get "BadTransformException: non-congruent transform above ViewPlatform"
> > >> >error message. I seem to get this randomly. Please let me know what's
> > >> >causing this and anyway of fixing this. Thanks in advance.
> > >> >
> > >> >-Tachio
> > >> 'non-congruent transform means' that you are scaling differently on the
> > >> axes Tachio (rather than translating). This is OK on the object side of
> > >> the scene graph, but is not allowed on the view side. Somewhere in the API
> > >> specs (and I can't remember where) it says that trying to scale the view
> > >> platform transform in a non-uniform way is not allowed, so you get the
> > >> exception.
> > >>
> > >> Tony
> > >
> > >That's strange, I have only rotation/translation transforms above
> > >ViewPlatform. Well, I hope it was a bug in 1.1.1 which 1.1.2 fixed.
> > >
> > >-Tachio
> > >
> > A bug in the API is quite possible Tachio - it wouldn't be the first. And
> > I suppose there could be some other reason for the exception - hard to tell
> > without the code. But 'non-congruent' does mean scaling according to the
> > published API and my maths books. I'm far from an expert in matrix
> > operations though. Maybe there's someone out there who can suggest how a
> > scaling can be produced from other ops. if it isn't just a bug.
> >
> > Tony
> >
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>
> --
> Ellery Chan <[EMAIL PROTECTED]>
> Harris ISD, Melbourne, FL 32904
> Voice: 407-984-6506, Fax: 407-984-6353
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